Removed HOTPLUG=1 from the monitor hotplug rules.
Since udev didn't understand this key, it wasn't using it anyway.
This gets rid of the confusing error message in /var/log/messages.
BUG=chromium-os:13694
TEST=Plugged/unplugged a VGA monitor and made sure modes still switched.
...also, built with FEATURES=keepwork and checked this file:
/build/x86-mario/tmp/portage/sys-fs/udev-151-r6/work/udev-151/udev/udev-rules.c
...validated that the unknown key was actually being ignored by udev, so this doesn't change behavior (other than getting rid of the error message).
Review URL: http://codereview.chromium.org/6825017
Change-Id: I20fa098407299b0f0ff5cf06e95089fa0c8a7f5a